http://browserdiet.com/

• avoid inline code
• styles up top, scripts down bottom
• minify your html
• try out async and defer
• minify your stylesheets
• combining multiple css files
• prefer over @import
• think about (and rethink) your key selector
• load 3rd party content asynchronously
• cache array lengths
• avoid document.write
• minimize repaints and reflows
• minify your script ....

还有很多

此外可以安装 YSlow 测试是否达标